Subs with Acoustic Zen Crescendos?

Any one use these speakers with a sub (s) and if so which ones and where have you crossed it over at?

rsf50711-15-2013 1:28pm

tls49 Details Discussions Posts This discussion Message User 1,351 posts 11-15-2013 at 05:41pm Copy Comment URL Report Comment Edit Delete The Acoustic Zen Crescendo low end specification is listed at 20Hz +/-3db. Why would you need a sub? Would you care to list the rest of your system?